High energy forming vacuum chamber



Dec. 23, 1969 v. v. KISELEV ETAL HIGH ENERGY FORMING VACUUM CHAMBER 2 Sheets-Sheet 1 Filed Oct. 18, 1967 All] FIE. 1

Dec. 23, 1969 v. KISELEV ETAL 3,

HIGH ENERGY FORMING VACUUM CHAMBER Filed Oct. 18, 1967 2. Sheets-Sheet 2 United States Patent HIGH ENERGY FORMING VACUUM CHAMBER Vasily Vasilievich Kiselev, Orekhovo-Zuevsky raion,

poselok Demikhovo, Moskovskaya Oblast, U.S.S.R.;

and Alexandr Yakovlevich Ryabukha, Rezervny proezd, 14, kv. 39; and 'Anatoli Ivanovlch Brylev,

Dobrovolcheskaya ulitsa, 13, kv. 5, both of Moscow, U.S.S.R.

Filed Oct. 18,1967, Ser. No. 676,162

Int. Cl. B2111 26/08 US. CI. 7256 t 6 Claims ABSTRACT OF THE DISCLOSURE A high energy forming vacuum chamber containing a die on which is placed a workpiece, a bath being in contact with the workpiece on the side thereof opposite the die, the bath containing an explosive. The chamber is formed with an upper dome portion which rises to a substantial height above the surface of the liquid of the bath. A conical depending portion extends from the dome at the center thereof towards the bath, but is still at a substantial distance above the surface of the bath so as to distribute water which rises due to the explosion of the explosive uniformly over the surface of the dome. Water is collected after it passes through an annular space around the die at the bottom of the chamber and is returned to the bath.

This invention relates to high energy forming vacuum chambers.

The conventionally known high energy forming vacuum chambers comprise a fixture in which a workpiece, for example, a metal sheet is placed. The fixture holding the sheet is immersed in water, while an explosive is placed in the water above the sheet. The shock wave generated as a result of the explosion is transmitted to the metal sheet through the water, said metal sheet being instantaneously pressed against a die or other similar device, thus acquiring a desired shape. The vacuum chamber top is domeshaped so that it corresponds to the shape of the shock wave front, while the walls of the chamber are cylindrical (ref., for example, US. Patent No. 3,068,822, class 113-44, dated 1960).

Upon the charge explosion, a water column is thrown up towards the chamber dome with a relatively high speed, the energy of the impact being concentrated mainly at the center part of the dome, above the center of the explosion.

In order to absorb the energy of the impact, the dome of the chamber as well as the chamber walls are made exceptionally strong. The weight of the vacuum chambers is as high as 75 tons and more.

An object of this invention is the elimination of the above disadvantage and the provision of such a vacuum chamber for high energy forming of metal sheets which, though comparatively simple in design and construction, is relatively light in weight and has relatively small overall dimensions.

In accordance with this invention, the above object has been achieved by the provision of a cone-shaped projection in the dome of the chamber directly above the explosive, the apex of said projection facing the explosive.

In a preferable embodiment of vacuum chamber in accordance with this invention, the walls of the projection are preferably smoothly merged with the chamber dome, while the dome is smoothly merged with the chamber side walls.

A test model of the vacuum chamber constructed according to this invention and intended for forming a semi- 3,485,075 Patented Dec. 23, 1969 ice elliptical bottom having a diameter of 1600 mm. and a depth of 480 mm. from an 8-mm. steel sheet, has walls and a dome whose thickness is not more than 10 mm., the weight of the chamber being not more than 3 tons. The chamber is suitable for making 1500 explosions of brisant charges, weighing not less than 1.8 kg. each without any repair.

The accompanying drawing contains schematic diagrams of possible embodiments of the vacuum chamber according to this invention, given by way of example, in which:

FIG. 1 is a vertical section of the vacuum chamber for forming convex bottoms.

FIG. 2 is a vertical section of an embodiment of the vacuum chamber for forming reservoirs.

The vacuum chamber consists of two halves, viz., the lower half 1 (FIG. 1) and the upper half 2 which are tightly connected with the aid of a flanged joint 3 compressed by means of wedges 4. The lower half 1 accommodates a die 5 which carries a workpiece being essentially a metal sheet 6. Installed atop the sheet 6 is a removable water reservoir 7 connected to the die 5 by means of rods 8 and wedges 9. The reservoir 7 is filled with water, and a brisant explosive 10 is placed in the water, said explosive being connected to an electrical detonation system.

The lower half 1 of the chamber communicates with a vacuum pump and a water-drain pump (the pumps and communication means are not shown in the drawing).

A dome 11 of the upper half 2 of the vacuum chamber has a cone-shaped projection 12, said projection being located above the explosive 10, the apex 13 of said pro jection 12 facing the explosive 10. The walls of the projection 12 smoothly merge into the dome 11, while the dome 11 smoothly merges into the side walls 14 of the upper half 2. There is a circular gap 15 between the walls 14 and the water reservoir 7.

Owing to the presence of the projection 12 in the dome 11, the mass of the water thrown up as a result of the explosion of the explosive 10 is uniformly distributed all over the chamber dome (as shown by the arrows in the drawing), so that the specific pressure upon the chamber dome is comparatively low.

After the explosion, the water flows down through circular gap 15 into the lower half 1 of the vacuum chamber, wherefrom the water drain pump forces the Water back into the reservoir 7.

The dome 11 of the box-shaped design has strengthening ribs 16 which, in combination with adjacent walls 17 and 18 of the dome, form spaces 19 filled with plasticine or other viscous plastic material. Since the speed of the shock wave propagation in the plastic material is lower than in metal, no concentration of the energy of impact occurs, so that the wall 17 is subjected to deformation with a certain time delay.

In the case of vessel forming, for example, of a spherical shape, a workpiece having the shape of a cylinder 6a made from a metal sheet is placed in a die 5a, said cylindrical workpiece at the same time serving as a water reservoir.

We claim:

1. A high energy forming vacuum chamber comprising a hollow sealed body including an upper and a lower portion connected together, a die secured in said body, means for mounting a workpiece in said body adjacent said die, a liquid bath in said body in contact with said workpiece, an explosive submerged in said bath, said upper portion having an upper dome surface extending a substantial distance above the bath and. including a central cone-shaped projection extending downwardly towards said bath at the center thereof but still at a substantial distance above the level of the bath, said projection smoothly merging with the dome to distribute water which rises, due to explosion of the explosive, uniformly over the surface of the dome.

2. A chamber as claimed in claim 1, wherein said die forms an annular peripheral space in said body and the water which flows to the bottom of the body is returned to said bath.

3. A chamber as claimed in claim 2, wherein said body is subjected to a vacuum.

4. A chamber as claimed in claim 3, wherein said upper and lower portions include external flanges which are coupled together, a sealing gasket being interposed between said flanges.

5. A chamber as claimed in claim 1, wherein said upper portion includes spaced walls at said dome with a shock absorbing medium in the space between the walls.

6. A chamber as claimed in claim 1, wherein said die has a cavity adjacent said workpiece, on a side thereof opposite said bath, to receive the workpiece and shape the same under the pressure produced by the explosion of the explosive.

References Cited UNITED STATES PATENTS 3,068,822 12/1962 Orr et a1. 7256 3,126,623 3/1964 Merrill 7256 3,181,327 5/1965 Barnett et al 7256 RICHARD J. HERBST, Primary Examiner 

